Abstract: Tenebrio molitor L. is an important resource insect. Based on the cuticular color of 60-day-old larvae, the yellow- and black-color varieties of T. molitor were obtained through natural selection of 12 consecutive generations. In order to provide further scientific data for cultivating new good breeds, the growth, development, survivorship and food utilization of the two color varieties of T. molitor were studied at first. The hatch rate and pupation rate of the two color varieties showed no significant difference and were about 83% and 97% for both, respectively. But the emergence rate of the yellow-color variety (female, 95%; male, 91%) was strikingly higher than that of the black one (female, 82%; male, 83%). The developmental duration of eggs and pupae of both varieties was about 7 d and 10 d, respectively, showing no significant difference, too. But the larvae of the black-color variety developed faster and more orderly than the yellow ones. Larvae of the black-color variety went through 12-15 instars in all, while the yellow-color ones went through 12-17 instars. Most of them went through 14 instars, for both the yellow- and black-color varieties. In the yellow-color variety, there were 27% larvae with 14 instars, while 53% in the black-color variety. If taking the larvae with 14 instars into consideration, the whole developmental duration of the yellow- and black-color varieties from egg to adult was about 171 d and 151 d, respectively. The yellow-color larvae had an average food utilization efficiency significantly higher than that of the black ones. The average approximate digestibility, efficiency of converting digested food and efficiency of converting ingested food of larvae of the yellow-color variety were 66.5%, 50.6% and 33.6%, respectively, while those of larvae of the black-color variety were 62.1%, 46.8% and 29.1%, respectively. There were no significant differences in the growth and survival rates between varieties at the same day age. In conclusion, the black-color variety of T. molitor develops faster and more orderly than the yellow-color variety, while the yellow-color variety has an average food utilization efficiency significantly higher than that of the black-color one. The results provide some useful reference for breeding new good varieties of T. molitor.

Key words: Tenebrio molitor, color variety, growth rate, survival rate, developmental duration, food utilization efficiency